1. Field of the Invention
The invention relates to an instrument for the unipolar ablation of heart tissue.
2. Related Art of the Invention
In surgical heart therapy electrical ablation is utilized, e.g. for the treatment of arrhythmia. Electrical energy, preferably in form of high frequency current is conducted into the region of the heart tissue causing the arrhythmia, particularly the atrium, to selectively damage the tissue in order to eliminate the cause of the arrhythmia. For this, instruments with bipolar and with unipolar supply of HF-energy are known. Further, it is known that a rinsing liquid may flow through the instrument and be discharged at the distal end in the region of the electrode. The rinsing liquid, e.g. a Ringer solution or other electrolytic liquid, serves for cooling and, as the case may be, for improvement of the electrical conductivity between the electrode and the tissue.
In U.S. Pat. No. 5,782,760 an instrument of the previously mentioned kind is disclosed. This instrument is introduced into the heart of the patient through a blood vessel. Here the tube, which conducts the electrical energy and the rinsing liquid to the distal end, is constituted as a flexible catheter. In instruments which are introduced by means of an invasive surgical intervention through the thorax into the heart, the tube is constituted as a rigid shaft.